Sand blast machine



18, 1931- 5.15. GARRATT SAND BLAST MACHINE 2 Sheets-Sheet 2 Filed Oct. 2, 1928 INYENTOR. 56arr 62007 4:

Patented Aug. 18, 1931 ams STATES PATENT OFFICE.

seal nts-1v manner smarter; or MANCHESTER, a tent ve; Assrcnoa no a. w. J'Acx MAN 85 COMPANY LIMITED, OF TS ALFORZD'; ENGLAND" SAND BLAST raa crrrnn Application filed. October 2, 1928, Serial No. season and: 111' Great Britain dctober 3,- 1927.

This invention relates to improvements in sand blast apparatus and more particularly to the valve control thereof of the type in which one movement of a single lever controls the air supply valve, the filling valve and the abrasive regulating valve.

It has been found that for a given air pressure and size of nozzle that the maximum sand blasting efficiency is obtained when a n given amount of abrasive is flowing and the essential feature of the present invention is to provide a. positive linked mechanism whereby the opening of the abrasive regulating valve can be regulated to the position giving the greatest efliciency with the air pressure and nozzle employed.

The invention will be described with'reference to the accompanying drawings Fig. 1 is an outside elevation partly in section of a sand blast apparatus showing one form of the invention applied thereto.

Fig. 2 is an outside elevation partly in section of same at right angles to Fig. 1.

Fig. 3 is a section of abrasive valve H.

Fig. 4 is a plan of Fig. 1.

Fig. 5 is an outside elevation of the upper I part of a sand blast apparatus showing another form of the invention applied thereto.

Fig. 6 is a plan of same.

Figs. 7, 8 and 9 are detail views of the air control valve.

Abrasive is stored in a chamber L and delivered to a pressure chamber F by a valve F compressed air being also admitted to the pressure chamber through a valve B and passes from this chamber to a mixing chamber M by a pipe M. The abrasive is de-- livered to the mixing chamber M arranged 0 below the pressure chamber F by a regulating valve H.

In the arrangement shown in Figs. 1 to 4.-

an operating lever A is mounted on the spindle of the air control valve B. An arm or lever C is mounted on or forms part of the lever A and is connected by the link C to an arm oZ aiiixed to or forming part of a cam- D mounted on a fixed pivot (P. The cam D acts on a screw 6 carried on one end of the pivoted lever E, the other end e of which is .con ected to the rod controlling. the filling valve F. 4 p 7 I I T e'cam-D is provided with aslot d to receive a bolt 9 which can be adjusted laterally to any position in the slot. Thefaceof the canrD adjacent to the slot (1 is serrated so that when the position of the bolt 9 has been adjusted and the bolt tightenedup,- the serrations onthe face of the cam will prevent any movement of the bolt. I

The bolt 9 is pivotally connected to the upper end a long vertical rod G the lower end ,of which is pivotally connected to' a lever G 05 on which the cam oscillates and accord-i ingly a lesser or greatermovement will be impart-ed to the rod G on the movement of the operatinglhandle A,

The vertical rod G is preferably made in two or more parts connected together by y ascrew device g so that the rod G can be lengthened or shortened to compensa-te for the" different positions of the bolt g in the slot d I The operating, lever is preferably arranged so thatthe air valve B does not commence to open until the filling valve F through \which the abrasive passes tothe pressure chamber F ,isclosed.

The delivery outlet H of the abrasive reg= ulating valve H is formed separatel from the valve and capable of being a xed in any p'ositionrelative thereto without altering the position of the operating gear. With such arrangement the operating gear can be placed in any convenient position without it beingnecessary to reduce the efficiency ofthe apparatusby using additional bends in the pipe line from the discharge outlet H 1 In operation the filling valve F is closed when the air controlvalve B- and the abrasive regulating valve H are openand the.

abrasive regulatin valve is adjusted by movement of the boltg in the slot (1 in the cam' D to the position giving the greatest?- small according to the position of the adjust- Figs. 5 ,to 9,the vertical rod G is pivotally mounted on the cam D but is not adjustable in relation to the fixed pivotal on which the cam D oscillates and in order to adjust the regulating valve H an adjustable stop K is provided the position of which regulates the movement of the cam D and consequently the 7 amount which the valve H will open.

The cam D is formed with an arm d connected by the link G to the arm or lever G on the air regulating valve B on'which is mounted the operating lever A.

As in this arrangement the angular movement of the operating lever A varies for different positions of the regulating valve H it is necessary to construct the air valve B so that it will be full open to the air pressure Whether the angular movement of the lever is small or large. The valve B is therefore constructed with a stationary base B having an orifice b therein and a disc B rotated by the lever A having a slot 6 therein concentric with the periphery of the disc B Thus once the. slot 71 has uncovered the aperture 6 the aperture 6 will remain uncovered during any further movement of the leverrA whether such movement of the lever A be large or able stop K.

The only dilference between the operation of the device shown in Figs. 1 to 4 and that T shown in Figs. 5 to 9 is that instead of adjusting the bolt 9 in the slot (Z3 in the cam D in the former, the movement of the cam D is regulated by the stop K in the latter.

What I claim as my invention and desire to protect by Letters Patent is V 7 Sand blast apparatus comprising the combination with an abrasive storage chamber and a pressure chamber, a filling valve for delivering abrasive from the storage chamber to the pressure chamber, a valve for admitting compressed air to the pressure chamber, a mixing chamber below the pressure chamber, an outlet valve for the abrasive from the pressure chamber into the mixing chamber and an outlet pipe for the compressed air from the top of the pressure chamber to the mixing chamber of a single operating lever mounted on the air control valve, a 'cam' mounted on a fixed pivot which controls the filling valve and to which the operating lever is connected and a vertical rod for controlling the abrasive regulating valve adjustably mounted on the cam so that its distance from the pivot thereof can be regulated.

In testimony whereof I have hereunto set my hand this 21st day of September, 1928. STEPHEN ERNEST GARRATT. 

